Research On The Influence Of In-situ Stress On Coal Rock Blasting Effect

With the increase of coal mining depth in my country,the influence of ground stress on blasting load is gradually increasing,and more and more unsafe factors are encountered during coal mining.Therefore,the study of the blasting effect of coal rock under the action of in-situ stress can provide relevant theoretical basis for coal mining engineering and ensure the safety of coal mines.This paper takes a coal mine in northern Shaanxi as the research object,combining experimental research,theoretical analysis,numerical simulation,etc.Methods,the effect of in-situ stress on coal rock blasting effect was studied,the main contents are as follows:First of all,based on the SHPB impact test,the failure and deformation characteristics of coal rock under impact load are studied,and the elastic modulus and failure strength of coal rock under impact load are analyzed.The relationship between the dynamic parameters and the strain rate is based on the characteristics of the experimental stress-strain curve.Based on the overstress model,the dynamic constitutive model of coal rock under impact load is established,and the model is carried out through the experimental curve.Verify that the two agree well.Experimental research provides data and experimental basis for theoretical derivation and numerical simulation.Secondly,on the basis of existing theories,the factors affecting the destruction effect of blasting load on coal and rock are analyzed,the stress of coal and rock mass under the combined action of in-situ stress and blasting load is studied,and the conditions of coal and rock destruction are determined by applying Mises criterion.The factors affecting the blasting effect of coal and rock mainly include two types of coal rock properties and coexisting conditions;through theoretical derivation,the influence of in-situ stress on the blasting effect of coal and rock is mainly manifested as:due to the difference between the vertical and horizontal in-situ stress The range of coal-rock fissure circles presents an elliptical distribution;as the in-situ stress increases,the destruction effect of blasting loads gradually weakens.Finally,based on the results of experimental and theoretical derivation,the dynamic numerical simulation software ANSYS/LS-DYNA was used to study the destruction effect of blasting load on coal rock under different in-situ stress levels.It can be seen from the comparison of numerical simulation results that the in-situ stress is considered During operation,the pressure of coal rock under blasting load is significantly less than that without in-situ stress.As the burial depth increases,the in-situ stress gradually increases,and the sum of the stresses on the same particle of coal rock gradually decreases;lateral The influence of the pressure coefficient mainly shows that the vertical and horizontal directions are different from the pressure of the same mass point.The larger the lateral pressure coefficient,the greater the difference between the stresses in the two directions,and the stress area shows an elliptical distribution.